However, the severity and number of images held by offenders are not enough alone to assess the risk they pose or the sentence they should receive, the report said.

Ceop urged police forces to prioritise the investigation of anyone caught with child abuse images who has easy access to children.

West Midlands Police said it raided six addresses over the past two days as part of the operation.

Three people were arrested and four children "safeguarded" after 35 officers executed warrants across the force area in Wolverhampton, Birmingham, Solihull, Sandwell and Dudley.

A 47-year-old man was arrested in Wolverhampton, a 37-year-old man was arrested in Dudley and a 38-year-old man was arrested in Sandwell, all on suspicion of downloading indecent images of children.

All three have been released on police bail with strict conditions pending further enquiries, a spokesman said, and computers were seized from all addresses.

The raids related to suspected offences involving images, including the possession and distribution of indecent images of children, a spokesman said.

The force said Operation Tharsley was a joint operation between 42 police forces and officers from the Serious Organised Crime Agency (Soca), targeting people thought to be in possession of child abuse images.

Suspects in the West Midlands were identified through local investigations as well as intelligence received directly from Ceop.

Detective Inspector Kay Wallace, from the force's Child Online Safeguarding Team, said: "This type of work is going on every day across the West Midlands as we seek to tackle those who use the internet as a vehicle to offend against children be it grooming for sexual activity or making, possessing or distributing indecent images.

"We are committed to arresting suspects, seizing images and ensuring our children are protected from abuse."

Andy Baker of Ceop, added: "It is clear that those who possess indecent images also pose a significant risk to children and understanding and managing that risk is not an easy undertaking.

"However, when we bring together the latest intelligence picture, nationally coordinated police action and operational support from our colleagues in Soca, we are making the UK a more hostile place for those who are seeking to exploit our children.

"If offenders think that collecting child abuse images is something they can get away with, they need to think again.

"These arrests show once again how law enforcement is becoming increasingly coordinated, sophisticated and innovative in targeting those who commit these crimes.

"Operation Tharsley highlights the excellent work carried out by UK police forces on a daily basis and I've seen first-hand the passion and dedication of officers investigating these cases.

"With our transition into the National Crime Agency, we will continue to support forces with child abuse investigations and enhance the UK's response in combating child sexual exploitation."